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SIGPAUSE(2) | System Calls Manual | SIGPAUSE(2) |
NAME¶
sighold, sigignore, sigpause, sigrelse, sigset — legacy interface for signal managementLIBRARY¶
Standard C Library (libc, -lc)SYNOPSIS¶
#include <signal.h> intsighold(int sig); int
sigignore(int sig); int
xsi_sigpause(int sigmask); int
sigrelse(int sig); void (*)(int)
sigset(int, void (*disp)(int)); int
sigpause(int sigmask);
DESCRIPTION¶
This interface is made obsolete by sigsuspend(2) and sigaction(2) The sigset() function modifies signal dispositions. The sig argument specifies the signal, which may be any signal exceptSIGKILL
and
SIGSTOP
. The disp argument
specifies the signal's disposition, which may be
SIG_DFL
, SIG_IGN
, or the
address of a signal handler. If sigset() is used, and
disp is the address of a signal handler, the system adds
sig to the signal mask of the calling process before
executing the signal handler; when the signal handler returns, the system
restores the signal mask of the calling process to its state prior to the
delivery of the signal. In addition, if sigset() is used,
and disp is equal to SIG_HOLD
,
sig is added to the signal mask of the calling process
and sig 's disposition remains unchanged. If
sigset() is used, and disp is not
equal to SIG_HOLD
, sig is
removed from the signal mask of the calling process.
The sighold() function adds sig to the
signal mask of the calling process.
The sigrelse() function removes sig from
the signal mask of the calling process.
The sigignore() function sets the disposition of
sig to SIG_IGN
.
The xsi_sigpause() function removes sig
from the signal mask of the calling process and suspend the calling process
until a signal is received. The xsi_sigpause() function
restores the signal mask of the process to its original state before
returning.
The sigpause() function assigns sigmask
to the set of masked signals and then waits for a signal to arrive; on return
the set of masked signals is restored. The sigmask
argument is usually 0 to indicate that no signals are to be blocked.
RETURN VALUES¶
The sigpause() and xsi_sigpause() functions always terminate by being interrupted, returning -1 with errno set toEINTR
.
Upon successful completion, sigset() returns
SIG_HOLD
if the signal had been blocked and the
signal's previous disposition if it had not been blocked. Otherwise,
SIG_ERR is returned and
errno
set to indicate the error.
For all other functions, upon successful completion, 0 is returned. Otherwise,
-1 is returned and errno is set to indicate the error:
- [
EINVAL
] - The sig argument is not a valid signal number.
- [
EINVAL
] - For sigset() and
sigignore() functions, an attempt was made to catch or
ignore
SIGKILL
orSIGSTOP
.
SEE ALSO¶
kill(2), sigaction(2), sigblock(2), sigprocmask(2), sigsuspend(2), sigvec(2)STANDARDS¶
The sigpause() function is implemented for compatibility with historic 4.3BSD applications. An incompatible interface by the same name, which used a single signal number rather than a mask, was present in AT&T System V UNIX, and was copied from there into the X/Open System Interfaces (XSI) option of IEEE Std 1003.1-2001 (“POSIX.1”). FreeBSD implements it under the name xsi_sigpause(). The sighold(), sigignore(), sigrelse() and sigset() functions are implemented for compatibility with System V and XSI interfaces.HISTORY¶
The sigpause() function appeared in 4.2BSD and has been deprecated. All other functions appeared in FreeBSD 8.1 and were deprecated before being implemented.June 2, 1993 | Debian |